1. Field of the Invention
This invention relates to a binding member removing apparatus for removing a binding member such as a staple from a bundle of sheets of paper, and an automatic document feeder, a sheet processing apparatus, and an image forming apparatus which are provided with the binding member removing apparatus.
2. Description of the Related Art
Binding members such as clips, tapes, and staples of wire material furnished with opposite pointed ends are widely used for producing a book or a leaflet by binding collectively a bundle of a plurality, of sheets of paper. In the case of binding a bundle of sheets of paper with staples, the opposite end parts of each staple folded in the shape of three sides of a square are driven through the bundle of sheets of paper and they are then folded inward toward each other. The staples used in this case generally have their size vary according to the number of sheets of paper forming a bundle.
A binding member removing apparatus is used for the purpose of removing the stapes from the bundle of sheets of paper which has been bound with the staples. The binding member removing devices of this class are classified on account of the difference in the action of removing a staple into two types, i.e. the type for removing a staple by cutting off part of the bundle of sheets of paper containing the staple (JP-A-08-15,927, JP-A-06-186,807 etc. refer) and the type for removing a staple by forcing an inserting member between the bundle of sheets of paper and the staple and extracting the staple with the inserting member (JP-U-62-154,445 refers).
The binding member removing apparatus which is disclosed in JP-A-06-186,807 is adapted to cut out the bound part of the bundle of the document sheets together with the sheets of paper forming the document by causing the cutting force of a punching blade to act on the document sheets approximating closely to the staple. The binding member removing apparatus which is disclosed in JP-A-08-15,927 is adapted to cut the part of the bundle of document sheets bound with a staple in the shape of a ribbon along one edge of the bundle of document sheets including the part mentioned above.
The pull-out type binding member removing apparatus which is disclosed in JP-U-62-154,445 has the inserting member disposed on that of the opposite surfaces of the bundle of sheets of paper in which the opposite end parts of a staple are not positioned. This binding member removing apparatus pulls a staple out of a bundle of sheets of paper by passing one inserting member between the bundle of sheets of paper and the staple and jerking the inserting member in the direction of expelling the staple. It, therefore, is incapable of cutting and removing part of the bundle of sheets of paper. Here, the staple is pulled out of the bundle of sheets of paper downward, made to fall down the path of recovery under the weight of its own, and recovered in a receptacle.
The binding member removing apparatus which are disclosed in the official gazettes mentioned above are invariably provided each for an automatic document feeder (ADF). When the bundle of document sheets in a state bound with a staple is mounted on the ADF provided with the binding member removing apparatus, the staple is automatically removed and then the document sheets are conveyed one by one from the bundle of document sheets which have been set loose in consequence of the removal of the staple. The copying machine is then set copying document sheets.
The conventional binding member removing apparatus mentioned above, however, have various problems as follows.
Firstly, the binding member removing apparatus so adapted that the removed staple will fall down under its own weight requires the path of recovery to be positioned substantially directly below a removing unit which serves the purpose of removing the staple and, at the same time, requires this path to approximate as closely to perpendicularity as permissible. For the purpose of securing the path of recovery of this description, therefore, the removing unit is inevitably destined to suffer the freedom of disposition thereof to be restricted. Particularly, the ADF which is provided with the binding member removing apparatus is not capable of adopting a structure allowing the staple to be removed upward from a bundle of sheets of paper mounted on the ADF because the removing unit is required to assume its position beneath the staple and cause the staple to be extracted from the lower side of the bundle by all means. This requirement poses a problem to the ADF of the type which particularly requires the document sheets to be mounted with the image face thereof held upward. Generally, the bundle of document sheets which is bound as a bundle of sheets of paper has a staple driven therein from the image face side thereof. If the ADF is provided with the removing unit which is adapted to extract the staple from the lower side of the bundle, the effect of automating the ADF will be inevitably impaired because the bundle of document sheets requiring removal of the staple must be mounted temporarily as held downward, i.e. in the direction opposite the direction in which the bundle is mounted for the purpose of conveyance by the ADF and, after the subsequent extraction of the staple, the bundle must be reversed so as to turn the image faces of the document sheets upward.
Then, the ADF provided with the binding member removing apparatus of the type causing the removed staple to fall down under its own weight suffers the lower side of the ADF to be enlarged markedly because it requires a space for installing the path of recovery and the receptacle of recovery below the ADF. The ADF is generally disposed on the platen glass of a copying machine. For the purpose of allowing a large space to be provided below the ADF, therefore, it becomes necessary to devise a way of avoiding the occurrence of a large gap between the platen glass surface of the copying machine and the lower face of the ADF. As a result, the problems of readapting the construction of the ADF itself and altering the construction of the copying machine etc. ensue.
Secondly, the extraction type binding member removing apparatus must be provided with an inserting member which fits the staple. If the inserting member which does not fit the staple is forcibly used, the problem of not only rendering removal of a staple difficult but also possibly damaging the bundle of sheets of paper ensue.
This problem occurs not merely on the apparatus which effects removal of the binding member automatically but likewise on the manual binding member removing apparatus which effects removal of the binding member manually. That is, the manual binding operation necessitates preparation of as many removing apparatus as kinds of size of staple. As a result, it suffers an increase in cost.
Further, this problem occurs on the ADF which is provided with the binding member removing apparatus. To be specific, the apparatus which effects removal of the binding member automatically suffers an increase not only in cost but also in size of the apparatus itself because it requires a plurality of inserting members to be accommodated in the interior of the apparatus.
The binding member removing apparatus of the type which pulls a staple out of a bundle of sheets of paper by passing one inserting member between the bundle of sheets of paper and the staple and jerking the inserting member in the direction of expelling the staple has the problem of tending to inflict damage on the bundle of sheets of paper unless the inserting member is passed infallibly between the bundle of sheets of paper and the staple binding this bundle and then moved smoothly.
Thirdly, the conventional apparatus mentioned above have no consideration for the question as to what measure is to be taken when the apparatus fails to remove the binding member. It is thought that the ADF which is provided with the binding member removing apparatus produces no problem of any sort so long as the staple has been normally removed. If the ADF fails to remove the binding member, it will proceed to effect the action of conveying the bundle of sheets of paper notwithstanding the bundle is still kept bound with the staple. As a result, the sheets of paper in the process of conveyance bring such problems as blocking the path of conveyance, sustaining breakage, and inflicting damage to the ADF.
The ADF is generally provided for a copying machine or a scanner. If the staple which has escaped removal is left advancing onto the platen glass of the copying machine or the scanner, it will have the possibility of inflicting damage to the surface of the platen glass.
Fourthly, the binding member removing apparatus of the extraction type is so constructed that the staple having folded opposite end parts is extracted from one face side of the bundle of sheets of paper. It, therefore, requires the force to be used for erecting or raising the opposite end parts of the staple in addition to the force for simply giving a pull at the staple. In short, to be used for extracting the staple from the bundle of sheets of paper, the force must be relatively large. The drive mechanism which is provided with a motor or a gear train which is adapted to actuate the inserting member, therefore, suffers an increase in size and, by the same token, the binding member removing apparatus suffers an addition to the size thereof.
Further, the extraction type binding member removing apparatus has the possibility that when the staple having the opposite leading end parts thereof driven through the bundle of sheets of paper and then folded toward each other is extracted from one face side of the bundle of sheets of paper, the folded opposite leading end parts will inflict damage to the individual sheets of paper forming the bundle.